I have a Prusa i3 printer. Been using it for about 8 months with PLA filament. Works great. I decided to try ABS filament. The problem is the heatbed will not heatup, It will start to heatup and just go to 23 deg. The bed is a, PCB heatbed Mk2a. Using anduino frimware. Is there something in the firmware that has to be changed? Ed https://reprap.org/forum/read.php?4,478945,478945#msg-478945 Thu, 13 Aug 2026 23:00:44 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,478945,496662#msg-496662 https://reprap.org/forum/read.php?4,478945,496662#msg-496662 Plz help me ..]]> yogi17yd Reprappers Tue, 14 Apr 2015 06:27:36 -0400 https://reprap.org/forum/read.php?4,478945,482341#msg-482341 https://reprap.org/forum/read.php?4,478945,482341#msg-482341 reprap.org]

Look at this schematic and it will give you hopefully a better understanding. If you measure voltage from + of your D8 connector to ground on the board, you should have 12 volts, when the mostfet receives the signal (probably the 1 volt you mention) it opens the ground path to - of D8 connector, so like I said both in (D8 + and ground) and out (D8 + and - connectors) should always be 12 volts.

I don't know the value of the signal to the mosfet (I can try with my board and see if it matches your 1 volt, if so the definitely your mosfet is damaged.]]> ggherbaz Reprappers Wed, 11 Mar 2015 11:45:00 -0400 https://reprap.org/forum/read.php?4,478945,482320#msg-482320 https://reprap.org/forum/read.php?4,478945,482320#msg-482320
If Max bed power is set to 256 like in the example I posted before, you should have full cycle at mosfet (12 bolts constant).

The 1 volt you mentioned it's at what pin of your mosfet? Also when you refer 120 volts, I assume is at your power supply, but what is the wattage of the 12 volts supply? You need minimum of 300 watts to be able to powered the bed (9 amps) if your power supply is underpowered (less than 10 amps output) most likely it will get hot and shut down on you when you try to power the bed. But assuming you purchased the printer as a kit, it should have a capable power supply.

The one volt part it's where most likely your problem is, like I said, at both pins 1 and 2 you should have 12 volts with D8 + on pin 1 when off and on pin 2 when on, disconnect the bed from the board and check again the voltage. If still at 1 volt at output pin your mosfet is damaged, if the 1 volt is at pin 1 or input pin then there is something wrong with your board. If you get 12 volts without the bed then is your bed the one with problems.]]> ggherbaz Reprappers Wed, 11 Mar 2015 10:46:12 -0400 https://reprap.org/forum/read.php?4,478945,481851#msg-481851 https://reprap.org/forum/read.php?4,478945,481851#msg-481851 If you still thing it is the mosfet, what kind should I get. My boad is anduino. The led light goes on for a short time solid then goes out.
Ed]]> tobig11 Reprappers Tue, 10 Mar 2015 10:18:40 -0400 https://reprap.org/forum/read.php?4,478945,479536#msg-479536 https://reprap.org/forum/read.php?4,478945,479536#msg-479536 ggherbaz Reprappers Thu, 05 Mar 2015 12:34:52 -0500 https://reprap.org/forum/read.php?4,478945,479524#msg-479524 https://reprap.org/forum/read.php?4,478945,479524#msg-479524 tobig11 Reprappers Thu, 05 Mar 2015 12:00:38 -0500 https://reprap.org/forum/read.php?4,478945,479511#msg-479511 https://reprap.org/forum/read.php?4,478945,479511#msg-479511 ggherbaz Reprappers Thu, 05 Mar 2015 11:32:19 -0500 https://reprap.org/forum/read.php?4,478945,479503#msg-479503 https://reprap.org/forum/read.php?4,478945,479503#msg-479503
If your configuration h look like this:
#define TEMP_SENSOR_0 57
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 0

Sensor "bed" is 0 which means: no sensor.

// This sets the max power delived to the bed, and replaces the HEATER_BED_DUTY_CYCLE_DIVIDER option.
// all forms of bed control obey this (PID, bang-bang, bang-bang with hysteresis)
// setting this to anything other than 256 enables a form of PWM to the bed just like HEATER_BED_DUTY_CYCLE_DIVIDER did,
// so you shouldn't use it unless you are OK with PWM on your bed. (see the comment on enabling PIDTEMPBED)
#define MAX_BED_POWER 256 // limits duty cycle to bed; 256=full current

The last define here is 256 for the bed, if yours is less, changed to full and test.

If your configuration h looks good, then is definitely a dead mosfet. But don't worry, they are cheap and easy to change.]]> ggherbaz Reprappers Thu, 05 Mar 2015 11:21:15 -0500 https://reprap.org/forum/read.php?4,478945,479388#msg-479388 https://reprap.org/forum/read.php?4,478945,479388#msg-479388 Arduino board. Firmware is; Reprap firmware based on Sprinter and grbl.
All the red led comes on solid then goes out.]]> tobig11 Reprappers Thu, 05 Mar 2015 07:34:45 -0500 https://reprap.org/forum/read.php?4,478945,479086#msg-479086 https://reprap.org/forum/read.php?4,478945,479086#msg-479086 ggherbaz Reprappers Wed, 04 Mar 2015 15:21:45 -0500 https://reprap.org/forum/read.php?4,478945,479065#msg-479065 https://reprap.org/forum/read.php?4,478945,479065#msg-479065 Ed]]> tobig11 Reprappers Wed, 04 Mar 2015 14:30:48 -0500 https://reprap.org/forum/read.php?4,478945,478952#msg-478952 https://reprap.org/forum/read.php?4,478945,478952#msg-478952 Looks like is not getting power from the board. Check voltage going out to bed.
Is the LED lighting up solid or blinking?

It could be several things, from a bad mosfet, bad wiring connection or settings in firmware.]]> ggherbaz Reprappers Wed, 04 Mar 2015 10:51:56 -0500 https://reprap.org/forum/read.php?4,478945,478945#msg-478945 https://reprap.org/forum/read.php?4,478945,478945#msg-478945
Ed]]> tobig11 Reprappers Wed, 04 Mar 2015 10:36:57 -0500